/*
 * $HeadURL: http://svn.apache.org/repos/asf/httpcomponents/httpclient/trunk/module-client/src/main/java/org/apache/http/conn/ManagedClientConnection.java $
 * $Revision: 672969 $
 * $Date: 2008-06-30 18:09:50 -0700 (Mon, 30 Jun 2008) $
 *
 * ====================================================================
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *   http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing,
 * software distributed under the License is distributed on an
 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 * KIND, either express or implied.  See the License for the
 * specific language governing permissions and limitations
 * under the License.
 * ====================================================================
 *
 * This software consists of voluntary contributions made by many
 * individuals on behalf of the Apache Software Foundation.  For more
 * information on the Apache Software Foundation, please see
 * <http://www.apache.org/>.
 *
 */

package org.apache.http.conn;

import java.io.IOException;
import java.util.concurrent.TimeUnit;

import javax.net.ssl.SSLSession;

import org.apache.http.HttpClientConnection;
import org.apache.http.HttpHost;
import org.apache.http.HttpInetConnection;
import org.apache.http.conn.routing.HttpRoute;
import org.apache.http.params.HttpParams;
import org.apache.http.protocol.HttpContext;

/**
 * A client-side connection with advanced connection logic. Instances are
 * typically obtained from a connection manager.
 * 
 * @author <a href="mailto:rolandw at apache.org">Roland Weber</a>
 * 
 * 
 *         <!-- empty lines to avoid svn diff problems -->
 * @version $Revision: 672969 $
 * 
 * @since 4.0
 */
public interface ManagedClientConnection extends HttpClientConnection,
        HttpInetConnection, ConnectionReleaseTrigger {

    /**
     * Indicates whether this connection is secure. The return value is
     * well-defined only while the connection is open. It may change even while
     * the connection is open.
     * 
     * @return <code>true</code> if this connection is secure,
     *         <code>false</code> otherwise
     */
    boolean isSecure();

    /**
     * Obtains the current route of this connection.
     * 
     * @return the route established so far, or <code>null</code> if not
     *         connected
     */
    HttpRoute getRoute();

    /**
     * Obtains the SSL session of the underlying connection, if any. If this
     * connection is open, and the underlying socket is an
     * {@link javax.net.ssl.SSLSocket SSLSocket}, the SSL session of that socket
     * is obtained. This is a potentially blocking operation. <br/>
     * <b>Note:</b> Whether the underlying socket is an SSL socket can not
     * necessarily be determined via {@link #isSecure}. Plain sockets may be
     * considered secure, for example if they are connected to a known host in
     * the same network segment. On the other hand, SSL sockets may be
     * considered insecure, for example depending on the chosen cipher suite.
     * 
     * @return the underlying SSL session if available, <code>null</code>
     *         otherwise
     */
    SSLSession getSSLSession();

    /**
     * Opens this connection according to the given route.
     * 
     * @param route
     *            the route along which to open. It will be opened to the first
     *            proxy if present, or directly to the target.
     * @param context
     *            the context for opening this connection
     * @param params
     *            the parameters for opening this connection
     * 
     * @throws IOException
     *             in case of a problem
     */
    void open(HttpRoute route, HttpContext context, HttpParams params)
            throws IOException;

    /**
     * Indicates that a tunnel to the target has been established. The route is
     * the one previously passed to {@link #open open}. Subsequently,
     * {@link #layerProtocol layerProtocol} can be called to layer the TLS/SSL
     * protocol on top of the tunnelled connection. <br/>
     * <b>Note:</b> In HttpClient 3, a call to the corresponding method would
     * automatically trigger the layering of the TLS/SSL protocol. This is not
     * the case anymore, you can establish a tunnel without layering a new
     * protocol over the connection.
     * 
     * @param secure
     *            <code>true</code> if the tunnel should be considered secure,
     *            <code>false</code> otherwise
     * @param params
     *            the parameters for tunnelling this connection
     * 
     * @throws IOException
     *             in case of a problem
     */
    void tunnelTarget(boolean secure, HttpParams params) throws IOException;

    /**
     * Indicates that a tunnel to an intermediate proxy has been established.
     * This is used exclusively for so-called <i>proxy chains</i>, where a
     * request has to pass through multiple proxies before reaching the target.
     * In that case, all proxies but the last need to be tunnelled when
     * establishing the connection. Tunnelling of the last proxy to the target
     * is optional and would be indicated via {@link #tunnelTarget}.
     * 
     * @param next
     *            the proxy to which the tunnel was established. This is
     *            <i>not</i> the proxy <i>through</i> which the tunnel was
     *            established, but the new end point of the tunnel. The tunnel
     *            does <i>not</i> yet reach to the target, use
     *            {@link #tunnelTarget} to indicate an end-to-end tunnel.
     * @param secure
     *            <code>true</code> if the connection should be considered
     *            secure, <code>false</code> otherwise
     * @param params
     *            the parameters for tunnelling this connection
     * 
     * @throws IOException
     *             in case of a problem
     */
    void tunnelProxy(HttpHost next, boolean secure, HttpParams params)
            throws IOException;

    /**
     * Layers a new protocol on top of a {@link #tunnelTarget tunnelled}
     * connection. This is typically used to create a TLS/SSL connection through
     * a proxy. The route is the one previously passed to {@link #open open}. It
     * is not guaranteed that the layered connection is {@link #isSecure secure}
     * .
     * 
     * @param context
     *            the context for layering on top of this connection
     * @param params
     *            the parameters for layering on top of this connection
     * 
     * @throws IOException
     *             in case of a problem
     */
    void layerProtocol(HttpContext context, HttpParams params)
            throws IOException;

    /**
     * Marks this connection as being in a reusable communication state. The
     * checkpoints for reuseable communication states (in the absence of
     * pipelining) are before sending a request and after receiving the response
     * in it's entirety. The connection will automatically clear the checkpoint
     * when used for communication. A call to this method indicates that the
     * next checkpoint has been reached. <br/>
     * A reusable communication state is necessary but not sufficient for the
     * connection to be reused. A {@link #getRoute route} mismatch, the
     * connection being closed, or other circumstances might prevent reuse.
     */
    void markReusable();

    /**
     * Marks this connection as not being in a reusable state. This can be used
     * immediately before releasing this connection to prevent it's reuse.
     * Reasons for preventing reuse include error conditions and the evaluation
     * of a {@link org.apache.http.ConnectionReuseStrategy reuse strategy}. <br/>
     * <b>Note:</b> It is <i>not</i> necessary to call here before writing to or
     * reading from this connection. Communication attempts will automatically
     * unmark the state as non-reusable. It can then be switched back using
     * {@link #markReusable markReusable}.
     */
    void unmarkReusable();

    /**
     * Indicates whether this connection is in a reusable communication state.
     * See {@link #markReusable markReusable} and {@link #unmarkReusable
     * unmarkReusable} for details.
     * 
     * @return <code>true</code> if this connection is marked as being in a
     *         reusable communication state, <code>false</code> otherwise
     */
    boolean isMarkedReusable();

    /**
     * Assigns a state object to this connection. Connection managers may make
     * use of the connection state when allocating persistent connections.
     * 
     * @param state
     *            The state object
     */
    void setState(Object state);

    /**
     * Returns the state object associated with this connection.
     * 
     * @return The state object
     */
    Object getState();

    /**
     * Sets the duration that this connection can remain idle before it is
     * reused. The connection should not be used again if this time elapses. The
     * idle duration must be reset after each request sent over this connection.
     * The elapsed time starts counting when the connection is released, which
     * is typically after the headers (and any response body, if present) is
     * fully consumed.
     */
    void setIdleDuration(long duration, TimeUnit unit);

} // interface ManagedClientConnection
